Three-dimensional numerical simulation of particle acoustophoresis: COMSOL implementation and case studies

As a microfluidic-based noncontact manipulation and separation technique, acoustophoresis is the motion of the particles or cells within a host fluid under the effect of acoustic waves. Wave scattering off the particle surface generates both acoustic radiation forces and interparticle interaction forces that move the particles relative to the host fluid and each other, respectively. In this paper, an implementation in the commercial finite element software COMSOL Multiphysics for three-dimensional simulations of particle acoustophoresis is presented. Case studies with various particle types including rigid, compressible, elastic, core-shell and different particle geometries including spherical and spheroidal particles as well as pair-particle are simulated. The simulation results are verified by comparing the scattered velocity potential around the particle and the acoustic forces on the particle, against the existing analytical solutions. Furthermore, the COMSOL Livelink for MATLAB is utilized to implement an incremental simulation algorithm for the particle migration under the effect of a standing wave in a microchannel, based on the Stokes drag formula. The acoustophoretic motion simulations are performed for single particle and pair-particle case studies to demonstrate the presented implementation capabilities in modeling multi-particle tracking in real applications.